lkml.org 
[lkml]   [2017]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH -v5 04/14] futex: Use smp_store_release() in mark_wake_futex()
    Since the futex_q can dissapear the instruction after assigning NULL,
    this really should be a RELEASE barrier. That stops loads from hitting
    dead memory too.

    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    ---
    kernel/futex.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    --- a/kernel/futex.c
    +++ b/kernel/futex.c
    @@ -1288,8 +1288,7 @@ static void mark_wake_futex(struct wake_
    * memory barrier is required here to prevent the following
    * store to lock_ptr from getting ahead of the plist_del.
    */
    - smp_wmb();
    - q->lock_ptr = NULL;
    + smp_store_release(&q->lock_ptr, NULL);
    }

    static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter,

    \
     
     \ /
      Last update: 2017-03-04 11:09    [W:4.128 / U:0.276 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site